A conventional inkjet printing system includes a printhead and an ink supply which supplies liquid ink to the printhead. The printhead ejects ink drops through a plurality of orifices or nozzles and toward a print medium, such as a sheet of paper, so as to print a dot of ink on the print medium. Typically, the orifices are arranged in one or more arrays such that properly sequenced ejection of ink from the orifices causes characters or other images to be printed upon the print medium as the printhead and the print medium are moved relative to each other. In one arrangement, commonly referred to as "on-axis" printing, the ink supply is an integral element with the printhead. In another arrangement, however, commonly referred to as "off-axis" printing, the ink supply is a separate, self-contained ink container connected with the printhead by, for example, a flexible tube. With an off-axis printing system, the mass of the printhead is sharply reduced such that the cost of a printhead drive system and an overall size of a printer can be minimized, and a speed of printing can be increased. In addition, separating the ink supply from the printhead allows the ink to be replaced as it is consumed without requiring replacement of the costly printhead.
A conventional self-contained ink container for an off-axis printing system typically includes a pressure vessel and a collapsible ink reservoir, in the form of a bladder or bag, disposed within the pressure vessel for holding a supply of liquid ink therein. As such, a pressurized air system releases pressurized air into the pressure vessel and around the ink reservoir to collapse the ink reservoir and deliver ink to the printhead. The potential exists, however, for the collapsible ink reservoir to develop a leak. The leak could result, for example, from a pin hole in the collapsible ink reservoir, a rupture of the collapsible ink reservoir, and/or a defective seal of the collapsible ink reservoir. Unfortunately, if a leak does develop, ink can escape from the collapsible ink reservoir. If the ink container is installed with the printing system, ink escaping from the collapsible ink reservoir can enter and contaminate the pressurized air system. If the ink container is separate from the printing system, ink escaping from the collapsible ink reservoir can spill from the pressure vessel.
Accordingly, a need exists for secondary containment of liquid ink disposed within a collapsible ink reservoir of a self-contained ink container. More specifically, a need exists for containing liquid ink which could leak from the collapsible ink reservoir within the ink container and for preventing the liquid ink from spilling outside of the ink container.